1. Field of the Invention
The present invention relates to a small size apparatus for measuring and recording acceleration, especially, an apparatus which is suitable for recording fine time changes in acceleration applied to a body. Further, the present invention relates to a memory medium detecting system for detecting a memory medium attached to the small size apparatus for recording the fine time changes in acceleration.
Further, the present invention relates to a method for carrying out a zero gravity experiment by using a space shuttle or a trajectory (or parabolic) flight of an aircraft, wherein the zero gravity experiment system is free floating from the space shuttle or the aircraft.
2. Description of the Related Arts
Recently, a zero gravity environment has been used for the purpose of developing new material. This is because in zero gravity, a physical phenomena which can not be obtained on earth, such as convection of a solution or fusion, or the phenomena in which the deposit of a crystal formed therein can be easily caused so that a novel material can be created. For the provision of a zero gravity environment, an experiment in space using, for example, a space shuttle which is a NASA project, or a first material experimental project (FMPT), are ideal. Zero gravity experiments can also be carried out, using the trajectory of an aircraft, or a short period of zero gravity during free fall of an experimental system in a deep vertical hole.
However, even with the above methods, although the gravity applied to the body is nearly zero, it is usually 1.times.10.sup.-5 .about.1.times.10.sup.-3 G in a vertical free fall experiment, 1.times.10.sup.-6 .about.1.times.10.sup.-3 G in a space (cosmic) experiment, and 1.times.10.sup.-4 .about.1.times.10.sup.-2 G in an aircraft experiment. Further in the above methods, although acceleration in a vertical direction toward earth may produce near zero gravity, a small value of acceleration will remain. Therefore, when using these methods, it is important to record the acceleration change from time to time to determine the exact characteristics of the experiment. Also, experiments in a zero gravity environment are quite restricted in both time and cost. Therefore, it is desirable to obtain suitable data with a minimum number of experiments, and to collect data regarding acceleration changes for the purpose of improving the reliability of experimental results.
Conventionally, for the purpose of measuring acceleration, a measuring and recording apparatus having a dimension of 80 cm.times.80 cm.times.40 cm and a weight of 20 kg was required. This apparatus comprises an amplifier which amplifies the signal from an acceleration sensor, an AD converter which converts the signal from the amplifier to a digital signal, an external-memory device for storing the acceleration change data, and a pen type recorder or the like.
Such a conventional large and heavy acceleration measuring apparatus is acceptable for measuring the acceleration of an entire space ship (such as a space shuttle) or an entire aircraft, but when the measurement of a local acceleration in a restricted space is required, the use of such a large apparatus is not suitable.
Therefore, for measuring acceleration changes for zero gravity experiments such as in the development of materials as mentioned above, the conventional large type measuring apparatus cannot be applied to only a certain portion of an experiment. Thus the acceleration data obtained is the data of the acceleration change in the entire space ship or aircraft. However, this cannot precisely indicate the acceleration at a special position at which a special phenomena happens, so that the quality of the experiment is restricted.
For the purpose of overcoming these problems, a method using a conventional acceleration measuring and recording apparatus in which, for example, the acceleration sensor portion is divided into a control portion and a recording portion, and these portions are connected by a cable, is considered. However, in such case, disturbance of the system due to vibration and the like applied externally via the cable cannot be avoided. Thus, reliable data cannot be obtained. Further, when measuring speed, a high speed visual record using a video-camera or the like, cannot be obtained.
On the other hand, recent advances in semiconductor techniques have resulted in improved CMOS type static RAMs (a memory element which can be randomly written into or read from). This RAM has increased density and low power dissipation. As one example in which an characteristic features of this S-RAM are used, a method of constructing the external memory instead of a medium such as a magnetic tape, a magnetic disc, a floppy disc and the like, by using the S-RAM, is considered.
A characteristic feature of this S-RAM is high speed so that when used in a computer system, access time for a program or data can be considerably decreased compared with conventional techniques. Further, as there are no moving parts, the life span and reliability are increased. Further, in actual use in the computer system, the memory can be comprised of a single circuit board "RAM card".
To determine the correct connection of the RAM card, additional circuit connections or an optical or photo detector are conventionally used.
However, in the former case, since the number of connections must be increased, the size of the system must also be increased. On the other hand, in the latter method, since a light path must be provided for the photo detector, then it is difficult to construct a small size system. Even if the RAM card is positioned correctly, faulty connections could still exist which would not be detected by the photo detector.
Therefore, the conventional method is unfavorable as it is difficult to comprise a system using a RAM card that is small in size. On the other hand, in terms of reliability, the conventional method has a problem in that it is, difficult to definitely ascertain the connection state of the RAM card installed in the system.